The present invention generally relates to coupling mechanisms for tools and the like and more particularly to a mechanism for coupling an accessory attachment to a rotary hand tool.
There has been continued innovation and improvement in the research and design relating to power tools, particularly rotary hand tools of the type that are used in woodworking, metal working and the like. Representative products of this type are those produced by Dremel of Racine, Wis., which also produces many accessory attachments for such rotary hand tools. The rotary hand tools are generally cylindrical in shape and have a motor unit with a rotary output shaft that is configured for driving the various rotary tools such as small saw blades, sander discs, grout removal tools and various shaped cutting tool bits. There are also many accessory attachments that can be used in association with the rotary tools, with the accessory attachments being connected to the stationary nose end portion of the rotary tool. Among such accessory attachments are a grout-removing tool guide that conveniently positions the grout-removing bit relative to the tool guide so that a user can conveniently and effectively remove grout from between individual floor and wall ceramic tiles, for example. Also, a depth guide is a desirable accessory attachment that can be used with many types of cutting tools to limit the depth of penetration of the tool into a work piece or work surface.
While such accessory attachments have been available for many years, the manner in which the accessory attachments are coupled to the tool has been the subject of continuing efforts to provide a simple and effective mechanism for coupling or mounting the accessory attachments to the hand tool itself. In this regard, the necessity of tightening holding screws or utilizing multiple turns of a threaded coupling mechanism for coupling the accessory attachment to the rotary hand tool, while effective, are not considered to be particularly simple and convenient in many past designs.
The present invention is directed to a particularly simple, elegant and convenient accessory attachment mechanism for attaching an accessory attachment to a rotary hand tool of the type that has a stationary nose end portion adjacent the output shaft of the rotary hand tool. The present invention enables an accessory attachment to be placed on the stationary nose end portion and rotated by a small amount, such as xc2xc of a rotation or turn, to securely lock the accessory attachment into place.
More particularly, the present accessory attachment is provided with a pair of opposed inwardly protruding bosses on opposite sides of the inside of the accessory attachment, which bosses engage a pair of outwardly extended elongated arcuate teeth located on the nose end portion of the rotary hand tool, with each of the teeth extending approximately 90xc2x0 to 100xc2x0 of the circumference of the cylindrical nose end portion and being curved in the axial direction so that the center of the tooth is moved in the axial direction rearwardly or away from the end of the nose end portion.
Thus, during operation, when the accessory attachment is slipped onto the nose end portion, so that the bosses are adapted to engage the teeth, an approximately xc2xc rotation in either direction will engage the tooth and pull the accessory attachment in the rearward direction as a result of the curvature of the tooth, until it is pulled onto the nose end portion to its maximum extent. The accessory attachment also preferably includes at least two interior notches at the end of the accessory attachment that are configured for engaging a biased pin that is provided in the nose end portion of the rotary tool so that during the approximately xc2xc rotation, the end of the accessory attachment will engage and depress the pin until the pin is coextensive with the recess, whereupon it will be released to hold the accessory attachment in place. In the preferred embodiment, the recesses have ramped surfaces to enable a user to rotate the accessory attachment and thereby depress the pin and easily disconnect the accessory attachment with a relatively modest force.